kernel/fs/pstore/platform.c

   1 /*
   2  * Persistent Storage - platform driver interface parts.
   3  *
   4  * Copyright (C) 2007-2008 Google, Inc.
   5  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License version 2 as
   9  *  published by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #define pr_fmt(fmt) "pstore: " fmt
  22
  23 #include <linux/atomic.h>
  24 #include <linux/types.h>
  25 #include <linux/errno.h>
  26 #include <linux/init.h>
  27 #include <linux/kmsg_dump.h>
  28 #include <linux/console.h>
  29 #include <linux/module.h>
  30 #include <linux/pstore.h>
  31 #include <linux/zlib.h>
  32 #include <linux/string.h>
  33 #include <linux/timer.h>
  34 #include <linux/slab.h>
  35 #include <linux/uaccess.h>
  36 #include <linux/hardirq.h>
  37 #include <linux/jiffies.h>
  38 #include <linux/workqueue.h>
  39
  40 #include "internal.h"
  41
  42 /*
  43  * We defer making "oops" entries appear in pstore - see
  44  * whether the system is actually still running well enough
  45  * to let someone see the entry
  46  */
  47 static int pstore_update_ms = -1;
  48 module_param_named(update_ms, pstore_update_ms, int, 0600);
  49 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
  50                  "(default is -1, which means runtime updates are disabled; "
  51                  "enabling this option is not safe, it may lead to further "
  52                  "corruption on Oopses)");
  53
  54 static int pstore_new_entry;
  55
  56 static void pstore_timefunc(unsigned long);
  57 static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
  58
  59 static void pstore_dowork(struct work_struct *);
  60 static DECLARE_WORK(pstore_work, pstore_dowork);
  61
  62 /*
  63  * pstore_lock just protects "psinfo" during
  64  * calls to pstore_register()
  65  */
  66 static DEFINE_SPINLOCK(pstore_lock);
  67 struct pstore_info *psinfo;
  68
  69 static char *backend;
  70
  71 /* Compression parameters */
  72 #define COMPR_LEVEL 6
  73 #define WINDOW_BITS 12
  74 #define MEM_LEVEL 4
  75 static struct z_stream_s stream;
  76
  77 static char *big_oops_buf;
  78 static size_t big_oops_buf_sz;
  79
  80 /* How much of the console log to snapshot */
  81 static unsigned long kmsg_bytes = 10240;
  82
  83 void pstore_set_kmsg_bytes(int bytes)
  84 {
  85         kmsg_bytes = bytes;
  86 }
  87
  88 /* Tag each group of saved records with a sequence number */
  89 static int      oopscount;
  90
  91 static const char *get_reason_str(enum kmsg_dump_reason reason)
  92 {
  93         switch (reason) {
  94         case KMSG_DUMP_PANIC:
  95                 return "Panic";
  96         case KMSG_DUMP_OOPS:
  97                 return "Oops";
  98         case KMSG_DUMP_EMERG:
  99                 return "Emergency";
 100         case KMSG_DUMP_RESTART:
 101                 return "Restart";
 102         case KMSG_DUMP_HALT:
 103                 return "Halt";
 104         case KMSG_DUMP_POWEROFF:
 105                 return "Poweroff";
 106         default:
 107                 return "Unknown";
 108         }
 109 }
 110
 111 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
 112 {
 113         /*
 114          * In case of NMI path, pstore shouldn't be blocked
 115          * regardless of reason.
 116          */
 117         if (in_nmi())
 118                 return true;
 119
 120         switch (reason) {
 121         /* In panic case, other cpus are stopped by smp_send_stop(). */
 122         case KMSG_DUMP_PANIC:
 123         /* Emergency restart shouldn't be blocked by spin lock. */
 124         case KMSG_DUMP_EMERG:
 125                 return true;
 126         default:
 127                 return false;
 128         }
 129 }
 130 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
 131
 132 /* Derived from logfs_compress() */
 133 static int pstore_compress(const void *in, void *out, size_t inlen,
 134                                                         size_t outlen)
 135 {
 136         int err, ret;
 137
 138         ret = -EIO;
 139         err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
 140                                                 MEM_LEVEL, Z_DEFAULT_STRATEGY);
 141         if (err != Z_OK)
 142                 goto error;
 143
 144         stream.next_in = in;
 145         stream.avail_in = inlen;
 146         stream.total_in = 0;
 147         stream.next_out = out;
 148         stream.avail_out = outlen;
 149         stream.total_out = 0;
 150
 151         err = zlib_deflate(&stream, Z_FINISH);
 152         if (err != Z_STREAM_END)
 153                 goto error;
 154
 155         err = zlib_deflateEnd(&stream);
 156         if (err != Z_OK)
 157                 goto error;
 158
 159         if (stream.total_out >= stream.total_in)
 160                 goto error;
 161
 162         ret = stream.total_out;
 163 error:
 164         return ret;
 165 }
 166
 167 /* Derived from logfs_uncompress */
 168 static int pstore_decompress(void *in, void *out, size_t inlen, size_t outlen)
 169 {
 170         int err, ret;
 171
 172         ret = -EIO;
 173         err = zlib_inflateInit2(&stream, WINDOW_BITS);
 174         if (err != Z_OK)
 175                 goto error;
 176
 177         stream.next_in = in;
 178         stream.avail_in = inlen;
 179         stream.total_in = 0;
 180         stream.next_out = out;
 181         stream.avail_out = outlen;
 182         stream.total_out = 0;
 183
 184         err = zlib_inflate(&stream, Z_FINISH);
 185         if (err != Z_STREAM_END)
 186                 goto error;
 187
 188         err = zlib_inflateEnd(&stream);
 189         if (err != Z_OK)
 190                 goto error;
 191
 192         ret = stream.total_out;
 193 error:
 194         return ret;
 195 }
 196
 197 static void allocate_buf_for_compression(void)
 198 {
 199         size_t size;
 200         size_t cmpr;
 201
 202         switch (psinfo->bufsize) {
 203         /* buffer range for efivars */
 204         case 1000 ... 2000:
 205                 cmpr = 56;
 206                 break;
 207         case 2001 ... 3000:
 208                 cmpr = 54;
 209                 break;
 210         case 3001 ... 3999:
 211                 cmpr = 52;
 212                 break;
 213         /* buffer range for nvram, erst */
 214         case 4000 ... 10000:
 215                 cmpr = 45;
 216                 break;
 217         default:
 218                 cmpr = 60;
 219                 break;
 220         }
 221
 222         big_oops_buf_sz = (psinfo->bufsize * 100) / cmpr;
 223         big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
 224         if (big_oops_buf) {
 225                 size = max(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),
 226                         zlib_inflate_workspacesize());
 227                 stream.workspace = kmalloc(size, GFP_KERNEL);
 228                 if (!stream.workspace) {
 229                         pr_err("No memory for compression workspace; skipping compression\n");
 230                         kfree(big_oops_buf);
 231                         big_oops_buf = NULL;
 232                 }
 233         } else {
 234                 pr_err("No memory for uncompressed data; skipping compression\n");
 235                 stream.workspace = NULL;
 236         }
 237
 238 }
 239
 240 static void free_buf_for_compression(void)
 241 {
 242         kfree(stream.workspace);
 243         stream.workspace = NULL;
 244         kfree(big_oops_buf);
 245         big_oops_buf = NULL;
 246 }
 247
 248 /*
 249  * Called when compression fails, since the printk buffer
 250  * would be fetched for compression calling it again when
 251  * compression fails would have moved the iterator of
 252  * printk buffer which results in fetching old contents.
 253  * Copy the recent messages from big_oops_buf to psinfo->buf
 254  */
 255 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
 256 {
 257         size_t total_len;
 258         size_t diff;
 259
 260         total_len = hsize + len;
 261
 262         if (total_len > psinfo->bufsize) {
 263                 diff = total_len - psinfo->bufsize + hsize;
 264                 memcpy(psinfo->buf, big_oops_buf, hsize);
 265                 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
 266                                         psinfo->bufsize - hsize);
 267                 total_len = psinfo->bufsize;
 268         } else
 269                 memcpy(psinfo->buf, big_oops_buf, total_len);
 270
 271         return total_len;
 272 }
 273
 274 /*
 275  * callback from kmsg_dump. (s2,l2) has the most recently
 276  * written bytes, older bytes are in (s1,l1). Save as much
 277  * as we can from the end of the buffer.
 278  */
 279 static void pstore_dump(struct kmsg_dumper *dumper,
 280                         enum kmsg_dump_reason reason)
 281 {
 282         unsigned long   total = 0;
 283         const char      *why;
 284         u64             id;
 285         unsigned int    part = 1;
 286         unsigned long   flags = 0;
 287         int             is_locked = 0;
 288         int             ret;
 289
 290         why = get_reason_str(reason);
 291
 292         if (pstore_cannot_block_path(reason)) {
 293                 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
 294                 if (!is_locked) {
 295                         pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
 296                                        , in_nmi() ? "NMI" : why);
 297                 }
 298         } else
 299                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 300         oopscount++;
 301         while (total < kmsg_bytes) {
 302                 char *dst;
 303                 unsigned long size;
 304                 int hsize;
 305                 int zipped_len = -1;
 306                 size_t len;
 307                 bool compressed;
 308                 size_t total_len;
 309
 310                 if (big_oops_buf && is_locked) {
 311                         dst = big_oops_buf;
 312                         hsize = sprintf(dst, "%s#%d Part%u\n", why,
 313                                                         oopscount, part);
 314                         size = big_oops_buf_sz - hsize;
 315
 316                         if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,
 317                                                                 size, &len))
 318                                 break;
 319
 320                         zipped_len = pstore_compress(dst, psinfo->buf,
 321                                                 hsize + len, psinfo->bufsize);
 322
 323                         if (zipped_len > 0) {
 324                                 compressed = true;
 325                                 total_len = zipped_len;
 326                         } else {
 327                                 compressed = false;
 328                                 total_len = copy_kmsg_to_buffer(hsize, len);
 329                         }
 330                 } else {
 331                         dst = psinfo->buf;
 332                         hsize = sprintf(dst, "%s#%d Part%u\n", why, oopscount,
 333                                                                         part);
 334                         size = psinfo->bufsize - hsize;
 335                         dst += hsize;
 336
 337                         if (!kmsg_dump_get_buffer(dumper, true, dst,
 338                                                                 size, &len))
 339                                 break;
 340
 341                         compressed = false;
 342                         total_len = hsize + len;
 343                 }
 344
 345                 ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
 346                                     oopscount, compressed, total_len, psinfo);
 347                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 348                         pstore_new_entry = 1;
 349
 350                 total += total_len;
 351                 part++;
 352         }
 353         if (pstore_cannot_block_path(reason)) {
 354                 if (is_locked)
 355                         spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 356         } else
 357                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 358 }
 359
 360 static struct kmsg_dumper pstore_dumper = {
 361         .dump = pstore_dump,
 362 };
 363
 364 /*
 365  * Register with kmsg_dump to save last part of console log on panic.
 366  */
 367 static void pstore_register_kmsg(void)
 368 {
 369         kmsg_dump_register(&pstore_dumper);
 370 }
 371
 372 static void pstore_unregister_kmsg(void)
 373 {
 374         kmsg_dump_unregister(&pstore_dumper);
 375 }
 376
 377 #ifdef CONFIG_PSTORE_CONSOLE
 378 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 379 {
 380         const char *e = s + c;
 381
 382         while (s < e) {
 383                 unsigned long flags;
 384                 u64 id;
 385
 386                 if (c > psinfo->bufsize)
 387                         c = psinfo->bufsize;
 388
 389                 if (oops_in_progress) {
 390                         if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
 391                                 break;
 392                 } else {
 393                         spin_lock_irqsave(&psinfo->buf_lock, flags);
 394                 }
 395                 memcpy(psinfo->buf, s, c);
 396                 psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, 0, c, psinfo);
 397                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 398                 s += c;
 399                 c = e - s;
 400         }
 401 }
 402
 403 static struct console pstore_console = {
 404         .name   = "pstore",
 405         .write  = pstore_console_write,
 406         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 407         .index  = -1,
 408 };
 409
 410 static void pstore_register_console(void)
 411 {
 412         register_console(&pstore_console);
 413 }
 414
 415 static void pstore_unregister_console(void)
 416 {
 417         unregister_console(&pstore_console);
 418 }
 419 #else
 420 static void pstore_register_console(void) {}
 421 static void pstore_unregister_console(void) {}
 422 #endif
 423
 424 static int pstore_write_compat(enum pstore_type_id type,
 425                                enum kmsg_dump_reason reason,
 426                                u64 *id, unsigned int part, int count,
 427                                bool compressed, size_t size,
 428                                struct pstore_info *psi)
 429 {
 430         return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,
 431                              size, psi);
 432 }
 433
 434 /*
 435  * platform specific persistent storage driver registers with
 436  * us here. If pstore is already mounted, call the platform
 437  * read function right away to populate the file system. If not
 438  * then the pstore mount code will call us later to fill out
 439  * the file system.
 440  */
 441 int pstore_register(struct pstore_info *psi)
 442 {
 443         struct module *owner = psi->owner;
 444
 445         if (backend && strcmp(backend, psi->name))
 446                 return -EPERM;
 447
 448         spin_lock(&pstore_lock);
 449         if (psinfo) {
 450                 spin_unlock(&pstore_lock);
 451                 return -EBUSY;
 452         }
 453
 454         if (!psi->write)
 455                 psi->write = pstore_write_compat;
 456         psinfo = psi;
 457         mutex_init(&psinfo->read_mutex);
 458         spin_unlock(&pstore_lock);
 459
 460         if (owner && !try_module_get(owner)) {
 461                 psinfo = NULL;
 462                 return -EINVAL;
 463         }
 464
 465         allocate_buf_for_compression();
 466
 467         if (pstore_is_mounted())
 468                 pstore_get_records(0);
 469
 470         pstore_register_kmsg();
 471
 472         if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
 473                 pstore_register_console();
 474                 pstore_register_ftrace();
 475                 pstore_register_pmsg();
 476         }
 477
 478         if (pstore_update_ms >= 0) {
 479                 pstore_timer.expires = jiffies +
 480                         msecs_to_jiffies(pstore_update_ms);
 481                 add_timer(&pstore_timer);
 482         }
 483
 484         /*
 485          * Update the module parameter backend, so it is visible
 486          * through /sys/module/pstore/parameters/backend
 487          */
 488         backend = psi->name;
 489
 490         module_put(owner);
 491
 492         pr_info("Registered %s as persistent store backend\n", psi->name);
 493
 494         return 0;
 495 }
 496 EXPORT_SYMBOL_GPL(pstore_register);
 497
 498 void pstore_unregister(struct pstore_info *psi)
 499 {
 500         pstore_unregister_pmsg();
 501         pstore_unregister_ftrace();
 502         pstore_unregister_console();
 503         pstore_unregister_kmsg();
 504
 505         free_buf_for_compression();
 506
 507         psinfo = NULL;
 508         backend = NULL;
 509 }
 510 EXPORT_SYMBOL_GPL(pstore_unregister);
 511
 512 /*
 513  * Read all the records from the persistent store. Create
 514  * files in our filesystem.  Don't warn about -EEXIST errors
 515  * when we are re-scanning the backing store looking to add new
 516  * error records.
 517  */
 518 void pstore_get_records(int quiet)
 519 {
 520         struct pstore_info *psi = psinfo;
 521         char                    *buf = NULL;
 522         ssize_t                 size;
 523         u64                     id;
 524         int                     count;
 525         enum pstore_type_id     type;
 526         struct timespec         time;
 527         int                     failed = 0, rc;
 528         bool                    compressed;
 529         int                     unzipped_len = -1;
 530
 531         if (!psi)
 532                 return;
 533
 534         mutex_lock(&psi->read_mutex);
 535         if (psi->open && psi->open(psi))
 536                 goto out;
 537
 538         while ((size = psi->read(&id, &type, &count, &time, &buf, &compressed,
 539                                 psi)) > 0) {
 540                 if (compressed && (type == PSTORE_TYPE_DMESG)) {
 541                         if (big_oops_buf)
 542                                 unzipped_len = pstore_decompress(buf,
 543                                                         big_oops_buf, size,
 544                                                         big_oops_buf_sz);
 545
 546                         if (unzipped_len > 0) {
 547                                 kfree(buf);
 548                                 buf = big_oops_buf;
 549                                 size = unzipped_len;
 550                                 compressed = false;
 551                         } else {
 552                                 pr_err("decompression failed;returned %d\n",
 553                                        unzipped_len);
 554                                 compressed = true;
 555                         }
 556                 }
 557                 rc = pstore_mkfile(type, psi->name, id, count, buf,
 558                                   compressed, (size_t)size, time, psi);
 559                 if (unzipped_len < 0) {
 560                         /* Free buffer other than big oops */
 561                         kfree(buf);
 562                         buf = NULL;
 563                 } else
 564                         unzipped_len = -1;
 565                 if (rc && (rc != -EEXIST || !quiet))
 566                         failed++;
 567         }
 568         if (psi->close)
 569                 psi->close(psi);
 570 out:
 571         mutex_unlock(&psi->read_mutex);
 572
 573         if (failed)
 574                 pr_warn("failed to load %d record(s) from '%s'\n",
 575                         failed, psi->name);
 576 }
 577
 578 static void pstore_dowork(struct work_struct *work)
 579 {
 580         pstore_get_records(1);
 581 }
 582
 583 static void pstore_timefunc(unsigned long dummy)
 584 {
 585         if (pstore_new_entry) {
 586                 pstore_new_entry = 0;
 587                 schedule_work(&pstore_work);
 588         }
 589
 590         mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
 591 }
 592
 593 module_param(backend, charp, 0444);
 594 MODULE_PARM_DESC(backend, "Pstore backend to use");